The role of auditory feedback in speech development: A study of compensation strategies for a lip-tube perturbation

Abstract

The role of auditory feedback in speech development was investigated through a study of compensation strategies for a lip-tube perturbation. Acoustic, articulatory, and perceptual analyses of the vowels /i/, /y/, and /u/ produced by ten 4-year-old French speakers and ten adult French speakers were conducted under two conditions: normal and with a 15-mm-diameter tube (for /y/ and /u/) or a 5-mm-diameter tube (for /i/) inserted between the lips. Ultrasound and acoustic recordings of isolated vowels were made in normal condition before any perturbation (N1), for each of the 20 trials in the perturbed condition (P), and in normal condition after the perturbed trials (N2). Data reveal that adult participants moved their tongue in the P condition more than children subjects, to compensate for F1 and F2 alteration induced by the tube. Except for /y/, the perturbation was generally at least partly compensated during the perturbed trials in adults and children, but children did not show a typical learning effect. Results are analyzed from the perspective of (i) goal specification in speech production in the acoustic and/or somatosensory domain, and (ii) the maturity of representations of the motor apparatus in the brain.